What does "HI PERF PASS" on 1970 402 mean? - Chevelle Tech
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post #1 of 6 (permalink) Old Jun 28th, 06, 9:53 PM Thread Starter
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Question What does "HI PERF PASS" on 1970 402 mean?

On a 402 CEO replacement block dated May 70, casting #3969854, just above the oil filter it is stamped "HI PERF PASS". Does this mean is was the 350HP version, with corresponding cam, and a steel crank? Would it be a 2 or 4 bolt block? There are only 2 holes above the oil filter area. Thanks.


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post #2 of 6 (permalink) Old Jun 28th, 06, 11:39 PM
 
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Re: What does "HI PERF PASS" on 1970 402 mean?

The "Hi perf pass " doesen't mean anything special.....my block had that and was a 350hp with 2 bolt mains and a cast crank and my buddy had the same motor (CTW) with 4 bolt main/steel crank....I think it was the luck of the draw witch type you had...could be either one.
Steve
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post #3 of 6 (permalink) Old Jun 29th, 06, 10:12 AM Thread Starter
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Re: What does "HI PERF PASS" on 1970 402 mean?

Thanks Steve, was your block a 1970 and your friends also a 70 block? And was there a difference in the area above the oil filter between your block and your buddy's. On the older blocks the 4 bolts generally had a 1/2" pipe thread hole for an external oil cooler (to be added in race applications) and each had a 3/8" pipe thread hole for the Oil guage that was moved further forward on the 4 bolts. And each had a 1/2" coarce-threaded hole for the z-bar pivot. Do you know if the 70 402 4 bolts had this addition hole for a possible oil cooler in addition to the 2 holes for the oil guage and the z-bar pivot? Thanks.


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Last edited by Jim_66SS; Jun 29th, 06 at 10:25 AM.
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post #4 of 6 (permalink) Old Jun 29th, 06, 2:04 PM
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Re: What does "HI PERF PASS" on 1970 402 mean?

Quote:
Originally Posted by james a larson
On a 402 CEO replacement block dated May 70, casting #3969854, just above the oil filter it is stamped "HI PERF PASS". Does this mean is was the 350HP version, with corresponding cam, and a steel crank? Would it be a 2 or 4 bolt block? There are only 2 holes above the oil filter area. Thanks.
"Stamped"? Or "cast"?

Pretty much every "car" block was cast with "Hi Perf Pass"...

These blocks were destined for "High Performance" AND/OR regular performance "Passenger" applications, and NOT "High Performance passenger" applications as many people confuse it with...

Supposedly, the external "oil cooler" holes were not on every 4-bolt block, but I have never seen a "factory" 4-bolt without these holes, and I have never seen a 2 bolt with them (from 1960's/early 70's vintage engines).


Did the 350HP version still have the steel crank???

Once you go RAT, you never go back...
TC #1366

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post #5 of 6 (permalink) Old Jul 1st, 06, 10:55 AM
 
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Smile Re: What does "HI PERF PASS" on 1970 402 mean?

Hey James:
Yes to ALL of your quesions.....The block has the exterior oil set up as shown on the image.....this is a 854 block dated feb '70.

https://www.chevelles.com/forums/showthread.php?t=120849

The brass fitting is in the 1/2 NPT hole and the long 3/8 bolt is in the other(bolt was shown for location of hole).
When I had the eng rebuilt I replaced the cast with a steel one.Karl's block(buddys)had the same setup.
Hope this helps
Steve
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post #6 of 6 (permalink) Old Jul 1st, 06, 10:55 AM
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Re: What does "HI PERF PASS" on 1970 402 mean?

All big blocks got HIGH PERF cast into them, it's no indication of any certain HP level. My '72 402 (2 bolt 240 HP) has it, as well as the '68 (4 bolt 375 HP) sitting in my garage.

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